CVE-2008-0658 in OpenLDAP
Summary
by MITRE
slapd/back-bdb/modrdn.c in the BDB backend for slapd in OpenLDAP 2.3.39 allows remote authenticated users to cause a denial of service (daemon crash) via a modrdn operation with a NOOP (LDAP_X_NO_OPERATION) control, a related issue to CVE-2007-6698.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 08/05/2019
The vulnerability described in CVE-2008-0658 affects the BDB backend implementation within OpenLDAP's slapd daemon, specifically in the modrdn.c file. This issue represents a denial of service condition that can be triggered by authenticated remote attackers who manipulate the modify DN (modrdn) operation. The flaw occurs when a malicious user submits a modrdn request containing a NOOP (LDAP_X_NO_OPERATION) control, which is a legitimate LDAP control used to indicate that no operation should be performed. The vulnerability stems from inadequate input validation and handling within the BDB backend's processing of such operations, leading to a daemon crash that effectively denies service to legitimate users.
The technical implementation of this vulnerability involves the slapd daemon's BDB backend failing to properly validate or handle the NOOP control during modrdn operations. When the daemon receives a modrdn request with this control, the internal processing logic does not adequately account for the special nature of the NOOP control, causing memory corruption or invalid state transitions that ultimately result in a crash. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to resource exhaustion or system instability. The vulnerability is particularly concerning because it requires only authenticated access, meaning that users who have already established legitimate connections to the LDAP service can exploit this weakness.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on OpenLDAP services, as it allows attackers to disrupt service availability without requiring elevated privileges beyond authentication. The daemon crash resulting from exploitation can lead to complete service unavailability until manual intervention is performed to restart the slapd process. This makes the vulnerability particularly attractive to attackers seeking to perform disruptive attacks against directory services. The issue is related to CVE-2007-6698, indicating a pattern of similar vulnerabilities in the BDB backend implementation that suggests deeper architectural issues in how the daemon handles certain LDAP controls within modify operations. The attack vector requires network access to the LDAP service and valid authentication credentials, making it accessible to both internal and external threat actors who have gained access to legitimate user accounts.
Organizations should implement immediate mitigations including applying the relevant security patches released by OpenLDAP maintainers, which would address the improper handling of NOOP controls during modrdn operations. System administrators should also consider implementing network segmentation and access controls to limit exposure of LDAP services to only trusted networks and users. Monitoring should be enhanced to detect unusual patterns of modrdn operations with NOOP controls, which could indicate exploitation attempts. Additionally, implementing intrusion detection systems that can identify the specific attack patterns associated with this vulnerability would provide early warning capabilities. The mitigation strategy should also include regular security assessments of LDAP configurations and access controls to prevent unauthorized users from obtaining valid authentication credentials that could be used to exploit this vulnerability. This issue demonstrates the importance of comprehensive input validation in server-side applications and the potential for seemingly benign control operations to cause system instability when not properly handled within backend processing logic.